Ultra-processed foods linked to higher cancer risk, mortality

Greater intake of ultra-processed foods was associated with an increased risk for overall and site-specific cancer, particularly ovarian cancer, as well as cancer-related mortality, a study published in eClinicalMedicine found.

According to Kiara Chang, MSc, a faculty member of medicine at the Imperial College London School of Medicine, and colleagues, cancer cases are expected to reach 28.4 million by 2040.

“However, at least 50% of cancer cases could be potentially preventable and an unhealthy diet is a key modifiable risk factor,” they wrote.

Ultra-processed foods (UPFs) are among the most concerning dietary habits contributing to cancer burden, Chang and colleagues noted. UPFs, they added, are often “liable to overconsumption,” high in fat and low in whole foods.

“Besides their poorer nutritional composition, UPFs may additionally increase cancer risk through neo-formed contaminants during industrial processing, use of some controversial food additives, and certain materials of packaging implicated in exhibiting carcinogenic and/or endocrine disrupting properties,” they wrote.

To fill gaps in research on associations between UPFs and cancer, Chang and colleagues analyzed data from the U.K. Biobank. Their analysis included 197,426 participants who completed 24-hour recalls that assessed dietary intake five times between 2009 to 2012. They were followed until Jan. 31, 2021. The participants were aged 40 to 69 years, and 54.6% were women.

Overall, the mean UPF consumption was 22.9%, with the lowest and highest UPF consumption totals at 9.2% and 41.4%, respectively.

Chang and colleagues reported that for every 10 percentage-point increase in UPF consumption, there was a 2% increase in cancer incidence overall (HR = 1.02; 95% CI, 1.01-1.04) and a 19% increase in ovarian cancer incidence in women (HR = 1.19; 95% CI, 1.08-1.3).

Participants with the highest UPF consumption compared with the lowest had a:

• 7% (95% CI, 1.02-1.14) greater risk for overall cancer;
• 25% (95% CI, 1.01-1.57) greater risk for lung cancer;
• 52% (95% CI, 1.04-2.23) greater risk for brain cancer; and
• 63% (95% CI, 1-2.66) greater risk for diffuse large B-cell lymphoma.

Notably, those in the highest UPF consumption quartile also had lower risks for head and neck cancer when compared with those in the lowest (HR = 0.59; 95% CI, 0.41-0.85).

“Similarly, stratified analyses showed lower risk patterns for head and neck cancer among never smokers, ex-smokers and all alcohol consumption groups, but most findings did not reach statistical significance,” the researchers wrote.

An increase of 10 percentage points in UPF consumption was also associated with higher risks for:

• overall cancer mortality (HR = 1.06; 95% CI, 1.03-1.09);
• breast cancer mortality (HR = 1.16; 95% CI, 1.02-1.32); and
• ovarian cancer mortality (HR = 1.3; 95% CI, CI, 1.13-1.5).

Compared with the lowest UPF consumption quartile, the highest quartile had greater mortality risks for overall cancer (HR = 1.17; 95% CI, 1.05-1.3), lung cancer (HR = 1.38; 95% CI, 1.04-3.82), and ovarian cancer (HR = 1.91; 95% CI, 1.08-3.39).

Chang and colleagues noted there were several mechanisms that could explain the associations between greater risks for adverse cancer outcomes and higher UPF intake.

“Recommendations for cancer prevention [emphasize] the importance of nutritionally balanced diets involving greater consumption of vegetables and fruit, lower consumption of unprocessed red meat and avoidance of processed meat, besides other [behavioral] factors including alcohol consumption and smoking,” they wrote. “However, dietary patterns with a high UPF content are generally nutritionally inferior and are higher in energy, total and saturated fats, salt and free sugars and lower in fiber and several micronutrients.”

The researchers also highlighted growing evidence on the potential role of UPF in obesity and type 2 diabetes, “both of which are risk factors for many cancers including those of the digestive tract and some hormone-related cancers in women.”

Study limitations included the cohort not being nationally representative and overly representative of white populations, misclassifications of food items contributing to a limitation of food processing information and 37.1% of the cohort only having one 24-hour recall.

Chang and colleagues concluded that the findings help to demonstrate the importance of considering degrees of food processing in dietary patterns, while suggesting that limiting UPF consumption “may be beneficial to prevent and reduce the modifiable burdens of cancer.”